1. Field of the Invention
The present invention relates to a thermoplastic acrylonitrile-butadiene-styrene (ABS) resin composition with excellent release and colorability. More specifically, the present invention relates to a thermoplastic ABS resin composition comprising a base resin and polysiloxane masterbatches as release agents wherein the base resin contains two kinds of grafted conjugated diene rubbery polymers having different rubber sizes and distributions.
2. Description of the Related Art
Acrylonitrile-butadiene-styrene (ABS) resins are typical resins that are highly functional and can be used for general purposes. ABS resins are used in various applications, including automotive parts, electric/electronic components and general merchandise, due to their advantages in terms of impact strength, tensile strength, modulus of elasticity, etc. For use in such applications, ABS resins are generally molded by suitable techniques, such as injection and extrusion molding. In the case where a resin is used as a material for a product requiring high precision dimensions or a product having a complex shape by molding or automatic injection molding of a resin is performed at high speed, the releasability of the resin may greatly affect the productivity and quality of the molded product.
Suitable modification of molding processing conditions can partially solve the problems associated with releasability, and in most cases, it does not provide a satisfactory solution to the releasability problems. Further, even if the problem of poor releasability is satisfactorily solved, the molding cycle time is increased, which leads to low productivity.
In another attempt to solve the problem of poor releasability, the application of a release agent to a mold is suggested. However, in the case of a molded toy product for children, ingredients of the release agent may remain on the molded product and have a bad influence on the safety of children.
In an alternative attempt, a release agent is previously blended with a resin to improve the releasability of the resin. Higher fatty acids and metal salts thereof, polyoxypropylene glycols and silicone oils are known to be suitable for this purpose. However, when the release agent is added in an amount of 0.5 parts by weight or more, a balance in the basic physical properties of the resin may collapse and a portion of the release agent may migrate to the resin surface to contaminate the surfaces of a mold and a molded product or worsen the thermal stability of the resin.
Korean Patent No. 10-0632208 discloses that a silicone release solution containing an epoxy compound and a silane compound is coated on the surface of a polyester film to improve the releasability of the polyester film. This patent is distinguished from the present invention by its application and in that the releasability of the polyester film is improved by the coating of the particular compounds.
Further, Korean Patent No. 10-0493459 discloses that the addition of a resin, such as ABS, LLDPE or HDPE, to a polycarbonate (PC) resin improves the releasability, processability, economic efficiency, chemical resistance, etc. of the PC resin while maintaining the inherent advantages of the PC resin in terms of impact resistance, self-extinguishing properties, dimensional stability and heat resistance. This patent is somewhat distinguished from the present invention in that the releasability of the base resin is improved by the addition of a resin different from the base resin rather than by the addition of an additive.
Thus, there is an urgent need for a thermoplastic ABS resin composition that is prepared by previously adding an additive to a resin to improve the releasability of the resin and achieve good colorability and well-balanced physical properties.